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1- Department of Plant Protection, Faculty of Agriculture, Shahrood University of Technology
2- Department of Plant Protection, Faculty of Agriculture, Shahrood University of Technology ,shahroodm@gmail.com
2- Department of Plant Protection, Faculty of Agriculture, Shahrood University of Technology ,
Abstract: (128 Views)
This study examines changes in hemocyte profiles and phenoloxidase activity in larvae of Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) under conditions of starvation, dietary variation, and thermal stress in laboratory settings. T. absoluta-infected tomato fruits were collected from fields and transported to laboratory, where larvae were extracted from fruits after two generations of rearing, Hemolymph was extracted with a capillary tube and placed on a slide. Hemocytes were identified through Giemsa staining and observed under light microscopy at 40× magnification. Starvation stress was induced for 12 and 24 hours while the control group remained unstressed. Hemocyte counts were determined using a hemocytometer under light microscopy at 40× magnification. Starved larvae exhibited significantly reduced total hemocyte counts, plasmatocytes, and granulocytes compared to the control group. Larvae reared on eight tomato varieties (Superchef, Basimo, Hartiva, Berantta, Breivio, Gs15, 1012, and 8320) displayed variable hemocyte densities, with the highest counts observed in those fed on Superchef and Gs15 cultivars. For thermal stress experiments, third- and fourth-instar larvae were exposed to 28°C and 4°C for 12 and 24 hours. Control groups for third and fourth instar larvae maintained at 25 ± 1°C. In total hemocyte and granulocyte densities were significantly reduced across all thermal treatments compared to controls. Plasmatocyte counts in third-instar larvae subjected to 12 hours of heat stress (327.5±18 cell/mm3 hemolymph) and cold stress (320±34.3 cell/mm3 hemolymph) were higher than those in control (294.3±23.3 cell/mm3 hemolymph). Phenoloxidase activity exhibited a direct correlation with hemocyte alterations across all experimental conditions. This study provides a foundation for further investigations into the pest's physiological defense mechanisms.
Article Type: Original Research |
Subject:
Toxicology and Physiology
Received: 2024/12/4 | Accepted: 2024/01/11
Received: 2024/12/4 | Accepted: 2024/01/11
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